Duet 3 Spindle Control



  • Hi All,

    I'm trying to configure my Duet 3 to set my spindle speeds. I'm using a PWM to 0-10VDC board from the out9 pin on the Duet.

    I'm having trouble setting the PWM frequency for the spindle speed. I currently have a multimeter hooked up to the output pins of the PWM converter board, and below is a series of code that I've tried setting different frequencies, but getting more or less the same result in all cases.

    I expect to set the spindle speed to 6000rpm to get 2.5VDC on the pins.
    The board has a pair of jumpers to select between (what appears to be) 0-10V and 0-7.5V logic, I'm confident that I've got this selected right.

    Here's a link to the board i'm using: https://www.auscomtech.com.au/product/pwm-to-voltage-converter-module-0-100-to-0-10v-digital-to-analog-signal/

    M453 C"out9" F50
    M3 S6000
    Read: 4.94V
    
    M453 C"out9" F100
    M3 S6000
    Read: 4.93V
    
    M453 C"out9" F1000
    M3 S6000
    read: 4.87V
    
    M453 C"out9" F3000
    m3 s6000
    Read: 4.74V
    
    M453 C"out9" F10000
    M3 S6000
    Read: 4.62V
    
    M453 C"out9" F500000000
    m3 s6000
    Read: 6.00V
    
    M453 C"out9" F5
    m3 s6000
    Read: 5.96V
    
    M453 C"out9" ;No frequency
    M3 S8000
    Read: 7.43V
    
    M3 S10000
    Read: 8.26V
    
    M3 S12000
    Read: 8.24v
    
    
    

    Any suggestions?



  • To simplify the question. Is there any reason why changing the PWM frequency of the M453 command would have no effect on the output voltage - which is supposed to be proportionate to the PWM frequency (with its limits)?



  • @Gerrard said in Duet 3 Spindle Control:

    Is there any reason why changing the PWM frequency of the M453 command would have no effect on the output voltage - which is supposed to be proportionate to the PWM frequency (with its limits)?

    well, to be blunt - the voltage isn't proportional to the PWM frequency but rather the duty cycle.



  • I think you need to set your R value in M453 to your spindle max. Expected frequency for your controller is 1-3KHz so F needs to be between 1000-3000.
    PWM control is on the duty cycle of the wave not the frequency, frequency stays constant once you've set it.
    M453 is set once then speed changes done with M3.

    M453 C"out9" R12000 F2000
    M3 S12000 ;Should get 10V
    M3 S6000 ;Should get 5V



  • right... There's a gap in my understanding there. Thanks for clearing that up. I'll give that a shot this weekend.



  • Thanks, that worked.


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